Figure 1: On-chip optical nonreciprocity based on nonlinear dynamics near an exceptional point. | Nature Communications

Figure 1: On-chip optical nonreciprocity based on nonlinear dynamics near an exceptional point.

From: Extremely broadband, on-chip optical nonreciprocity enabled by mimicking nonlinear anti-adiabatic quantum jumps near exceptional points

Figure 1

(a) Basic operating scheme of the proposed concept. (b) Effective index modulation profiles over the unidirectional converter region for the attenuating (upper) and amplifying (lower) waveguides. (c,d) Two-dimensional numerical calculations (FEM, Comsol Multiphysics) assuming single-mode slab waveguides with the following optical parameters: cladding index of 1.50; core index of 1.55; core index modulation depth Δncore=6 × 10−4. The effective index modulation amplitude is given by Δn0=ΓΔncore and the confinement factor is Γ=0.71. Operation at the vacuum wavelength of 1,130 nm and in the fundamental transverse-electric mode (TE0) is assumed. The colour scale indicates intensity I in dB with respect to the incident intensity I0. The peak intensity of the incident mode is I0=IS for both the forward and backward transmission cases, where IS denotes a gain saturation intensity constant. (e) Cross-sectional profiles of the transmitted intensity in the forward and backward directions. The estimated nonreciprocal transmission ratio (NTR) is 28.7 dB and the forward transmission gain is 4.95 dB.

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